Electric-motor control.



Patented Mar. 13, |900.

F, A.;MEnmcK. ELECTRIC MOTOR CONTROL..

(Application led Aug. 1l, 18995) (No Model.)

m. m W

UNITED STATES PATENT EEICE FRANK A. MEEEICK, or Jo1-1NsTowN,PENNSYLVANIA, AssicNoE To THE LoEAIN sTEEL COMPANY, on PENNSYLVANIA;

ELECTRIC-MOTOR CONTROL..

SPECIFICATION forming part of Letters Patent No. 645,117, dated March13, 1906.

original dppiiddiidii iiiediipiii19,1e99, sdiidlno. 719,690. Divided andthis application filed Auguri 11. 1899. Serial Nl' To all 10790711, tmay' concern: Be it known that I, FEANKA.l\/IEEE1CK, of

Johnstown, in the county of Cambria and of which this application is adivision. That system, generally considered, comprises a method ofregulating the speed and acceleration of a plurality of electric motorswherein zo the motors are started in series and are shifted over toparallel by intermediate steps, whereby the field-windings are iirstconnected in parallel with the armature-steel in series, andsubsequently the armature-coils of the two motors are coupled inparallel with the held-windings in series. The system also includescertain other minor steps and cornbinations thereof.

The present invention provides means for carrying the said system intopractical operation in a satisfactory and efficient manner 5 and itconsists in the combination, with a plurality of electric motors, of acontrollingswitch therefor and circuit connections by which therelations of the motors and their elements may be changed, as described,by the operation of a single switch-handle.

Referring to the accompanying drawings, illustrating the invention,Figure 1 is a dia- 4o grammatic view showing two electric motors,

a controller, a reversing and cut-out switch, and such parts of thewiring and connections as are necessary to illustrate the nature andoperation of my invention. Fig. 2 is a simi- 45 lar view showing amodified form of controller. Fig. 3 shows the successive circuitconnections made by the movement of the controlling-switch shown inFig. 1. Positions Nos. 1, 2, 3, Li, 7, 10, and 12 of this ligure also ppatent, Serial No. 713,690, filed April 19, 1899, f

(No model.)

represent the successive circuit changes madel by the controller shownin Fig. 2.

In the figures, A A2 represent the armatures of the motors, and F F2 theeldcoils.- Squares l to 12 represent aseries of fixed con: tact-brusheswhich form part of the controlling-switch and which are arranged toengage with a series of movable contacts, (designated by c' to 026.)(These contacts may consist of contact-pieces secured to a rot-arycylindric drum operated by a suitable hand-lever. Controller-switches ofthe same type of mechanical construction are well known in the art, andit is sufficient to show and describe the arrangement of the movablecontacts. -These contacts are divided into ive groups, each of which iselectrically disconnected from the other groups, but has all itsindividual contacts electrically connected. Contacts c to c7, inclusive,constitute one group; contacts o8 09 c10 constitute a second group;contacts c11 to c, inclusive, a third group; contacts 018 to o23,inclusive, a fourth group, and contacts c25 and C26 a fifth group. Afurther single contact 024 is connected to ground through the shaft ofthe controller. 75

It will be noted that certain of the contacts while belongingelectrically to the one group with respect to position are within thelines of another group, so that certain of the brushes may engage withcontacts of two adjacent electrical groups. Brushes 6, 7, 8, 9, and 11are of this class. Certain of the contacts are also arranged to bebridged by the brush in certain positions. The purpose of this describedrelation of the contacts will be better understood after'the differentpositions of the controlling-switch have been examined.

B represents the coil of an electromagneticarc interrupter or blow-outthrough which the current passes to the controller and motor circuit andwhich is connected to the brush 1.

R represents an artificial resistance which I prefer to insert incircuit when the motors are first started and which is connected be- 95tween brushes 2 and 5 and also with brushes 3 and 4:. Armature A isconnected between the brushes 8 and 11. Armature A2 is conmaximumresistance.

nected to brush 10 upon one side and to ground upon the opposite side.

G' is a conductor which connects the brushes 6 and 12.

Z designates a group of moving contacts which form part of a combinedreversing and' cut-out switch, and squares 13 to 22 indicate the contact-brushes which cooperate with such contacts. This switch forms no partof the present invention further that than it is necessary to employsome switch of this character, and it need not, therefore, be describedin detail. For the purpose of tracing out the circuits hereinafter itwill be assumed that the brushes 13 to 22 are in engagement with thosecontacts Z which are on the vertical line Za and which are furtherdesignated as Z', Z2, the., to Z2, respectively. Brush 13 is connectedto brush 6 of the controller by conductor C2, the field-coils F2 areconnected between the brushes 14 and 1G, brush 15 is connected to brush1S by a conductor C2, brush 17 is connected to brush 9 by conductor C4,brush 18 is connected to brush 5 by conductor C5, field F' is connectedbetween brushes 19 and 20, brush 2l is connected to brush 7 by conductorC6, and brush-22 is connected to brush 11 by conductor C7.

At the first position of the switch brushes 1, 2, 6, 7, S, 9, 10, 11,and 12 are respectively engaged with the contacts c' c2 cl0 c14 015 C20022 c25 026, and the course of the current, assuming that the brushes 13to 22 are in the position Za, as above stated, is as follows: from thetrolley, through blow-out coil B, to brush 1, contacts c' c2, brush 2,resistance R, brush 5, connection C5, brush 18, contact Z5, contact Z7to brush 20, through field-windings F' to brush 19, to contact Z, tocontact Z8, brush 21, connection C6, to brush 7,contacts c14 015, brush8, through armature A', brushes 11, contacts c25 C26, brush 12, throughconnection C' to brush G, through conductor O2 to brush 13, to contactsZ' Z3, to brush 1G through field F2, to brush 14, to contacts Z2 Z4,brush 17, connection C4, brush 9, contacts 022 C22, to brush 1,0 througharmature A2 to ground G. It will be seen, therefore, that in thisposition the current flows through the blow-out coil, the artificialresistance, and the armatures and fields in series, so that themotor-circuit presents a In the next three positions the only changemade in the circuit is to gradually cut out the resistance R, as brushes3, 4, and 5 are respectively engaged with the respective contacts c3 cilc5, the resistance at the last position No. 4) being entirely cutout ofcircuit. I prefer to employ these preliminary steps wherein theresistance is gradually removed from the circuit as the counterelectromotive force of thc motors gradually increases; but they may bedispensed with, not, however, Without the disadvantage of a considerableinrush of current at the start. In the fifth position the brush 6 isbridging onto the contact c7 of the rst group, and the brushes 7 and 8still engage the contacts c1" 015, the result being that the currentdivides, one part passing by brush 5 through the motors in series, asbefore, and the other part by brush (i, conductor C2, brush 13, contactsZ' Z3 to brush 16, so that a shunt is thrown around one motor, and thevolume of current passing thro ugh the motor-circuit is considerablyincreased. The position 5fL illustrated in Fig. 3 is a momentaryposition only, in which the circuit through the first motor is broken bythe brushes 7 and 8, leaving the contacts c14 and C15 in passing toposition 6. In this latter position the circuit through the field of thefirst motor remains open, but its armature is connected in shunt witht-he circuit by reason of the brush 9 bridging over the contact c17 ofthe third group and the brush 11 engaging the contact c23of the fourthgroup, whereby the current after passing through F2 divides, one partgoing by brush 9, contacts 017 016, brush 8, through armature A', brush11, contacts c23 022, brush 10, through armature A2 to ground, and theother part going direct to brush 1-0 and armature A2 to ground. Inpassing from position 6 to position 7 the brush 9 entirely leavescontact 020, thereby breaking the short circuit around armature A' andsending the current in series through the two armatures, with the secondfield also in series therewith, the circuit through field F' remainingopen by reason of the fact that brush 7 is not engaged with any contact.This is the position of circuit relation denoted by (il. Positions 5, 5,6, and 6 are temporary or pass-over positions and IOO are passed overrapidly preparatory to establishing the connections shown by positionNo. 7 and effecting gradual decrease of circuit resistance. In positionNo. 7 brush 7 again becomes engaged with a contact (cl2) of the thirdgroup,and thereby restablishes the circuit through the first field. Aportion of the current, however, passes from contact c7 to brush 6 andcond uctor C2 and through the second field. The two currents-meet in thecontacts of the third group and pass through the two armatures in seriesto ground. It will be seen, therefore, that the two fields are inparallel with the two armatures in series, resulting in a decrease in.the strength of the fields and an increased flow of current. In passingfrom position 7 to position 8 the brush 6 leaves the contact chaudthereby cuts the field F2 out of circuit, the entire current passing bybrush 5 through the field F' and armatures A' A2, in series, by thecourse heretofore traced. This gives the condition of the circuit shownat 72. In position S the connections remain substantially as before,except that the brush 11 comes in contact with the contact 024, and thusestablishes a shunt to ground around the armature A2 through the shaftof thecontroller. In passing from position 8 to position 9 the brush 11leaves the contact o23 entirely, and thereby cuts armature A2out ofcircuit. But one motor is now in circuit. When position 9 is reached,the

brush 7 is bridging the contacts c cl2, so that after the current haspassed through the first field it divides, one path being from contacto8, brush S, rbc., through the second field to the third group ofcontacts,and hence through A', brush 11, contact 024 to ground, and theother path being a short circuit around the second field by way of brush8 to A', &C.,the brushes 8 and 9 bridging over onto the contacts c16 andc19 of the fourth group. Passing from position 9, brush 7 leaves thecontact cl3, thereby cutting out the shunt around the second field. Thecircuit is now in the condition shown at fJL-that is to say, elds F F2are connected in series with the armature A' and armature A2 remains outof circuit. Positions 71,8, `8a, 9, and 9a are temporary positionspreparatory to position 10. In position 10 the engagement of the brush10 with the contact c2l divides the current after it has passed inseries through the two fields, one part passing by the brush S throughA' to ground and the other part passing by brush 1.0 through A2 toground. The two fields are therefore Vconnected in series with the twoarmatures in parallel. In passing from position 10 the brush S leavesthe contact C18, thereby cutting the first armature out of circuit. Thisgives the momentary condition shown at 10a. When position 11 is reached,the brush 6 bridges onto the contact c6 of the first group, and therebyshort-circuits F', the other connections remaining as at position 10a.Passing from position 11, the brushes 6 and 7 leave the contacts a8 e9,and thereby break the connection between F' F2, and the entire currentpasses through F2 A2, as shown in position lla. Positions 10, ll, and 11are preliminary to making the final connections shown in position 12. Inthis position brushes 1, 5, 6, 7, 8, 9, 10, and 11 are respectivelyengaged with the contacts c' ci c'j c1l G12 c19 021 C24. The currentdivides at the brushes 5 and 6, one part passing by conductor C5, brush18, confacts Z5 Z7, brush 20, field F', brush 19, contacts Z6 Z2, brush21, conductor C, brush 7, contacts c11 012, brush 8, armature A andbrush 11 to ground, and the other part passing by conductor C2, contactsZ' Z2, brush 16, field F2, brush 14, contacts Z2 Z4, brush 17, conductorC4, brush 9, contacts 019 021, brush 10, and armature A2 to ground, thetwo motors as a whole being in parallel.

It will be observed, therefore, from the foregoing and from an analysisof Fig. 3, that starting with the motors connnected in series with eachother and with artificial resistance I gradually cut out the resistanceas the counter electromotive force increases, removing it entirely whenthe motor speed and the developed counter electromotivc force becomessufliciently high to permit the motors to be connected directly to thecircuit. I next by a series of subordinate changes of temporarycharacter decrease the resistance of the motor-circuit byshort-circuiting and cutting out the elements of one motor, againincreasing the resistance by reconnecting in the armature previously cutout preparatory to making the first multiple connection reached inposition No. 7, in which the fields are in multiple with the armaturesin series, the effect of which is a considerable acceleration of speed,controlled, however, by the series connection of the armatures. I thenagain reduce the resistance of the circuit by cutting out successivelyone field and one armature, reconnecting in the previously-cut-out fieldbefore making the next running position wherein the two elds are inseries with the two armatures in parallel. (Position No. 10.) Thisposition results in a further considerable acceleration of speed, butcontrolled by the series connection of the fields. I then again effectfurther subordinate changes, in which one armature and one field aresuccessively cut out preparatory to passing to the final position, inwhich the two motors as a whole are connected in multiple.

The temporary or pass-over positions above described I prefer to employin passing from one to the other of the comparatively-permanentpositions; but they may bc omitted, as will appear from the descriptionhereinafter given of the modified controller shown in Fig. 2. The otheror comparatively permanent conditions are known as runningpositions-that is to say, they are conditions which afford successiveregulating steps and may be maintained as long as it is desired toproceed at the rate of speed which they severally give.

It will also be observed that each particular group of contacts has itsparticular function to perform and although interrelated with adj acentgroups is to some extent an independent switch. Group No. 1 forms oneterminal of the motor-circuit. It also controls the resistance andoperates as a field-paralleling and shunt switch. Group No. 2 operatesto connect the two fields in series. Group No. 3 controls theconnections of armature A'. Group No. 4 controls the connection betweenthe field and armature of the motor A2 F2. Group No. 5 controls theseries connection of the two motors as awhole. Contact C24 operates as agrounding-switch for the armature A'.

In the modification shown in Fig. 2 the connections are the same as inFig. l, and the general construction of the controller is also the same.The arrangement and area of the contact is, however, somewhat modified.In place of the single extended contacts c c5 of the first group Iprovide shorter separated contacts ca cb cC cd and ce cf cg ch,respectively. Contacts c6 c7 08 09 cl3 c16 01B C20 o23 024 are madeshorter, and instead of the long contacts 019 021 shorter separatedcontacts c cj and ck c1 are employed. In place of the long contacts 022two shorter separated contacts cm cu are provided. The connectionsremain the same as in Fig. 1. The effect of these changes, as

will readily appear without tracing out the IOO several positions indetail, is to eliminate positions 5, 6, 6, 7, 8, S, 9, 9a, l0, ll, and1l, leaving positions l, 2, 3, 4t, 7, l0, and l2 the same as with thecontroller shown in Fig. l. In other words, after cutting out theexternal resistance the two elds are first connected in parallel. Theirseries connection is then restored and the two armatures are connectedin parallel, and, lastly, the two motors as a whole are connected inparallel. These, in fact, are the essential positions involved in theoperation of the controller shown in Fig. l, the intermediate stepsthere shown being for the purpose of preventing quite as abrupt changesand obtaining a more gradual acceleration of speed. In lieu of thesechanges, in the controller shown in Fig. 2 the circuit through thecontroller and the motors is momentarily broken inpassing from onepositionA to the next.

Having thus described my invention, what I claim as new, and desire toprotect by Letters Patent, is

l. The combination with a plurality of electric motors, of acontrolling-switch having electrically-disconnected groups of contacts gand connections arranged in different positions of the switch to connectthe motors in series, the armatures in series and the fields inparallel, or the fields in series and the armatures in parallel, or themotors as a whole in parallel, and also to remove or cut out of circuitone or more of the motor elements in passing from one of saidconnections to another.

2. The combination with a plurality of electric motors, of acontrolling-switch having electrically-disconnected groups of contactsand connections arranged in diierent positions of the switch to connectthe motors in series, the armatures in series and the iields inparallel; or the fields in'series and the armatures in parallel; or themotors as a whole in parallel. y

3. The combination with a plurality of electric motors, of acontrolling-switch having clectrically-disconnected groups of contactsand connections arranged in different positions of the switch to connectthe motors in series, the armature in series, and the elds in parallel,or the elds in series and the armatures in parallel, or the motors as awhole in parallel, and also to short-circuit and cut out either motor oreither element thereof.

4. The combination witha plurality of motors, and external resistance,of a switch having electrically-disconnected groups of contacts andconnections, said contacts and connections being arranged to connect themotors in series with and'without the external resistance, to connectthe corresponding pairs of motor elements in both series and parallelrelation to each other, and to connect the n10- tors as a Whole inparallel.

In testimony whereof I have afiixed my signature in presence of twowitnesses.

FRANK A. MERRIOK.

Vitnesses:

JOHN H. KENNEDY, H. W. SMITH.

